High dose toremifene in advanced breast cancer resistant to or relapsed during tamoxifen treatment

Fifty patients with advanced breast cancer refractory to prior tamoxifen therapy were assigned to investigational treatment with high-dose toremifene administered 120 mg orally twice a day. Treatment was generally well tolerated. The majority (80%) of the patients had no side effects, and among the remaining 10 patients reported side effects were mostly mild and/or transient. Two objective tumor responses were observed: one complete response (CR), duration 6.2 months, and one partial response (PR), duration 8 months. The response rate was thus 4% (95% CI: 0.5 to 14%). In addition 3 patients experienced a mixed response, some metastatic sites responding, while at other sites disease progressed; 22 patients had disease stabilization for > 2 months. A subset analysis disclosed that a small subgroup of patients, including 7 patients in this study, who had achieved CR at some of the sites during preceding tamoxifen therapy, experienced a long progression-free time during high dose toremifene treatment. The median time to progression in this subgroup of patients was 9.4 months (95% CI: 3.8 to 9.4) as opposed to 2.1 months (95% CI: 2.0 to 2.8) for all the remaining 43 patients, which is a significant decrease in disease progression (p < 0.03). Such results reveal that although this kind of second-line hormonal treatment with high dose toremifene cannot be recommended for all tamoxifen failures, there might be a subset of patients, i.e. those who achieve CR in some lesion during tamoxifen therapy, who benefit from this type of treatment.

Effect of Toremifene in patients with metastatic melanoma: a phase II study of the EORTC Melanoma Cooperative Group

The EORTC Melanoma Cooperative Group conducted a phase II trial (study number 18891) to study the effect of Toremifene in 45 patients with advanced, metastatic melanoma. Male and female patients, median age 61 (range 23-88) years received a mean total dose of 11 g (4.3-62.6) orally for at least 6 weeks. No objective remissions were seen. Four patients (3 women and 1 man; 9%) experienced 3-6 months' disease stabilization. The toxicity of the drug, given at a dose of 240 mg daily, was negligible. Because of the minimal side-effects, Toremifene may be recommended for patients who have only a small number of slowly growing metastases, in particular to soft tissue and lung.

Multicenter phase II efficacy trial of toremifene in tamoxifen-refractory patients with advanced breast cancer

PURPOSE

To explore further the efficacy of high-dose toremifene in patients with advanced breast cancer who had failed to respond to tamoxifen or whose disease had progressed on tamoxifen.

PATIENTS AND METHODS

One hundred two perimenopausal or postmenopausal women with metastatic breast cancer refractory to tamoxifen were entered onto a phase II clinical trial of toremifene at a dose of 200 mg/d. The study patients consisted of 28 primarily refractory patients; 43 patients who had relapsed after a prior tamoxifen response; and 31 patients who had relapsed while receiving adjuvant tamoxifen. This was a heavily pretreated group of patients, with 65% having failed chemotherapeutic attempts and 72% having failed two or more hormonal therapies. Forty-nine percent of patients had visceral dominant disease.

RESULTS

The objective response rate was 5% (95% confidence interval [CI], 3% to 7%). The median time to treatment failure (TTF) was 10.9 months for the five responders. An additional 23% of patients had stable disease for a median TTF of 7.8 months, whereas the patients who experienced treatment failure had a median TTF of 2.1 months. Whether those patients with stable disease derived clinical benefit or simply had slow progression in an intrinsically indolent disease presentation is uncertain. Common toxicities were generally mild and similar to those encountered with tamoxifen.

CONCLUSION

We conclude that there is major cross-resistance between tamoxifen and toremifene and that only occasional tamoxifen-refractory patients will have objective responses to toremifene.

Toremifene and tamoxifen in advanced breast cancer--a double-blind cross-over trial

Toremifene (TOR) is a triphenylethylene derivative related to tamoxifen (TAM). TOR has antitumor activity, not dependent on estrogen receptors, and responses with TOR have been observed in patients with progressive disease during TAM-treatment. To elucidate possible cross-resistance between these two antiestrogens, we compared their anti-tumor activity in a randomized, double-blind, cross-over study. 66 postmenopausal women with advanced estrogen receptor positive or unknown breast cancer and a median age of 63 years (range 38-82) were included. Patients were randomized to TAM 40 mg/day or TOR 240 mg/day. Treatment continued until progressive disease, when cross-over to the alternative treatment was done. The response rate with first line TOR was 29% (95% confidence limits 10-41%) and with TAM 42% (95% confidence limits 25-61%). Response rates and response durations, survival and toxicity were not significantly different between the two treatments. 44 patients progressing on first line TAM or TOR were evaluable for second line TOR or TAM treatment. As no responses were observed, the possibility of over-looking a response rate of 20% or more is less than 1%. In conclusion, this study strongly indicates that TOR and TAM are clinically cross-resistant in patients with advanced breast cancer.

[Phase II study of NK 622 (toremifene citrate) in advanced breast cancer, a multicentral cooperative dose finding study]

In order to determine the usual dose in the first line therapy and a high dose in the second or third line therapy, a dose finding study of a novel antiestrogen NK 622 (toremifene citrate) was performed in patients (pts) with advanced or recurrent breast cancer. NK 622 was orally administered daily once for more than 8 weeks. In pts without previous drug therapy or in pts with cancer relapse after adjuvant therapy, the response rates [(CR + PR)/total] were 24.1% (7/29), 13.8% (4/29), 20.0% (1/5) and 40.0% (2/5) at doses of 40, 60, 120 and 240 mg/day, respectively. A 40 mg/day dose showed an objective response only in postmenopausal pts with estrogen receptor (ER) positive or unknown cancer. At a dose of 60 mg/day, some of the responding cases were premenopausal pts or pts with ER(-) cancer. In pts with cancer relapse during adjuvant therapy or in those with previous therapy and/or radiation, response rates were 25.0% (2/8), 0% (0/4), 13.5% (5/37) and 10.3% (4/39) at doses of 40, 60, 120 and 240 mg/day, respectively. Response was more frequent in pts with ER (+) cancer than with ER (-) cancer. The response rates in pts with previous therapy including tamoxifen (TAM) except medroxyprogesterone (MPA) were 14.3% (4/28) at a 120 mg/day dose and 6.1% (2/33) at a 240 mg/day dose. In pts with previous therapy including TAM, MPA and other antitumor agents, the rate was 18.2% (2/11) at a 120 mg/day dose. Side effects such as elevation of GOT, GPT and serum Ca level, decrease of hemoglobin, anorexia, nausea/vomiting, fatigue, dizziness and hot flush were observed. These side effects were moderate in grade and reversible. Dose dependency of side effects was not clearly observed in grade and incidence. From these results, NK 622 is expected to be a safe drug with efficacy in first line therapy at a dose of 40 mg/day and in second or third line therapy at a dose of 120 mg/day.

[Phase I study of NK 622 (toremifene citrate)]

A phase I study of NK 622 (toremifene citrate), a novel antiestrogen, was conducted in female patients with cancer. Patients received a single oral dosing or daily once oral dosing for five consecutive days. Any adverse effects were not experienced in the single dosing of 40 or 60 mg of NK 622. In the daily administration of 10, 20, 40, 60, 120, 240 and 480 mg/day, one of three patients who received 20 mg/day experienced grade 1 anorexia, three of four patients received 240 mg/day experienced adverse effects: Grade 1 leukopenia in one patient, Grade 1 general hot flush in one patient, and Grade 1 nausea, hot flush in the face and vertigo, Grade 2 anorexia, fatigue, dull headache and general hot flush in another one patient. These symptoms recovered to normal levels after treatment. Serum hormone levels were examined in postmenopausal patients, and a significant increase of the sex hormone binding globulin level was observed in the patients received 120 and 240 mg/day doses. Serum levels of NK 622 determined as free base (TOR) reached the peak levels in 2 to 4 hours after administration on the 1st and 5th day in daily treatment, while a metabolite N-demethyltoremifene (TOR-1) reached the peak level in 4 to 170 hours. Maximum serum levels and area under the concentration versus time curves of TOR and TOR-1 increased dose-dependently. These values also increased by repetition of the treatment. Half-lives of TOR and TOR-1 in serum ranged in 74.5 to 148.9 hours and 154.1 to 653.1 hours, respectively. From these results, it was concluded that safety and efficacy of NK 622 should be assessed by using 240 mg or less doses in clinical phase II studies where breast cancer patients received long term treatment with NK 622.